Emergency brake mechanism

ABSTRACT

In an emergency brake mechanism of the present invention, a rotation input shaft is increased in rotation speed by a planetary set-up gear to centrifuge weights, so that through the action of the centrifugal force of the weights, linings of the brake shoes are brought into press-contact with a fixed portion, to reduce rotation of the rotation input shaft, such that a large braking power is produced for a compact emergency brake mechanism.

BACKGROUND OF THE INVENTION

[0001] 1. Technical Field of the Invention

[0002] The present invention relates to an emergency brake mechanism and particularly to a centrifugal emergency brake mechanism.

[0003] 2. Description of the Prior Art

[0004] In a generally known centrifugal emergency brake mechanism, brake shoes are pivotally supported to a rotation axis at one ends thereof, so that when the rotation axis is rotated, the brake shoes are centrifuged and swung outward, so as to bring part of the thus spread out brake shoes into press-contact with a fixed surface, so as to apply the friction to the rotation axis and put brake on it.

[0005] In this conventional centrifugal emergency brake mechanism, since the frictional force for the brake is generated by the centrifugal force generated by the mass of the brake shoes rotated, generation of a strong frictional force requires increase in mass of the brake shoes or in rotation speed of the same.

[0006] When an increased frictional force is produced by increasing the mass of the brake shoes, there arises the problem that the brake shoes and thus the entire emergency brake mechanism are increased in size, and as such is not suitable for installation on a compact brake mechanism.

[0007] On the other hand, when an increased centrifugal force is produced by increasing the rotation speed of the brake shoes, there arises the problem that it is practically infeasible to mount the emergency brake mechanism on the rotation axis of relatively low revolution (rotation speed), such as the rotation axis of a shutter used in a factory, warehouse and the like, or a rope winding shaft of a lift and the like on and from which an escape rope is wound and paid out.

[0008] If a heavyweight shutter is used for a factory or warehouse and when it is pulled down, the rotation axis gradually increases in rotation speed as the shutter paid out increases in length and in downward inertia force. As a result of this, when the bottom end of the shutter gets down to the ground, large impact and noises are produced and also possible accidents of one's fingers or toes being caught in or pinched between the shutter and the ground and injured or cut off may happen. In an escape lift having a gondola, for example, if the rotation axis of the escape lift gradually increases in rotation speed, the gondola is put in danger when landed.

[0009] In the light of the problems above, the present invention has been proposed. It is the object of the present invention to provide a centrifugal emergency brake mechanism of compact size that is applicable to a variety of devices and can produce an excellent braking power for the compact size.

SUMMARY OF THE INVENTION

[0010] In order to accomplish the object mentioned above, an emergency brake mechanism according to the present invention comprises a planetary set-up mechanism provided between a rotation input shaft and a fixed portion; weights; and brake shoes, wherein the brake shoes are so arranged on the rotation input shaft as to be in association with it and the weights are centrifuged by an increased rotation speed produced by the planetary set-up gear, so that through the action of the centrifugal force of the weights, friction surfaces of the brake shoes are brought into press-contact with the fixed portion, to reduce rotation of the rotation input shaft.

[0011] In the emergency brake mechanism mentioned above, frictional contact portions are formed in the brake shoes at portions thereof on the drive shaft side, so as to be directly or indirectly contacted with the drive shaft, and the portions of the brake shoes with which the frictional contact portions are brought into contact are formed in the form of slant locking surfaces.

[0012] In the emergency brake mechanism mentioned above, the rotation input shaft may be a winding shaft of a shutter and which may be so structured as to control a lowering speed of the shutter.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In the drawings:

[0014]FIG. 1 is a front view in outline of an emergency brake mechanism according to the present invention mounted on a shutter for an entrance of a warehouse;

[0015]FIG. 2 is an enlarged view of an emergency brake mechanism portion according to the present invention;

[0016]FIG. 3 is an enlarged longitudinal section of the emergency brake mechanism portion according to the present invention;

[0017]FIG. 4 is an exploded perspective view of a planetary set-up gear portion of the emergency brake mechanism according to the present invention;

[0018]FIG. 5 is a longitudinally sectioned side view of the emergency brake mechanism according to the present invention;

[0019]FIG. 6 is a sectional view taken along line A-A of FIG. 1;

[0020]FIG. 7 is a longitudinally sectioned side view of the emergency brake mechanism according to the present invention which is in the operation mode; and

[0021]FIG. 8 is a longitudinally sectioned side view of a variant of a lock mechanism of the emergency brake mechanism according to the present invention which is in the operation mode.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] In the following, description will be given to the preferred embodiments of the emergency brake mechanism according to the present invention with reference to the accompanying drawings.

[0023]FIG. 1 is a front view of an emergency brake mechanism of the present invention mounted on a shutter attached to a factory or warehouse; FIG. 2 is an enlarged view of an emergency brake mechanism portion according to the present invention; and FIG. 3 is an enlarged longitudinal section of the emergency brake mechanism portion.

[0024] In the drawings, reference numeral 1 denotes the entirety of the shutter with an emergency brake mechanism 2.

[0025] The shutter 1 has a blade portion 3 for covering an entrance 5 of a warehouse 4. The blade portion 3 is configured to be retractably taken up by a winding mechanism 6 provided at the top of the entrance 5 of the warehouse 4.

[0026] The winding mechanism 6 comprises an accommodating portion 8 covered with a cover 7, a drive shaft (rotation input shaft) 9 extending through the accommodating portion 8, a drive unit 10 provided at one end of the drive shaft 9, and a brake unit 11 provided at the other end of the drive shaft 9.

[0027] A take-up reel (not shown) is mounted on the drive shaft 9 extending through the accommodating portion 8, and an upper end portion of the blade portion 3 is connected to the take-up reel.

[0028] The drive unit 10 provided at the one end of the drive shaft 9 is composed of an electric motor 12, a reduction gear mechanism (not shown) for reducing the rotation speed of the electric motor 12, and a chain drive mechanism (not shown) for transmitting the reduced rotation to the drive shaft 9.

[0029] The brake unit 11 provided at the other end of the drive shaft 9 is composed of a planetary set-up gear 13 for increasing the rotation speed of the drive shaft (rotation input shaft) 9, a tubular casing (a fixed portion) 16 rotationally driven in association with the drive shaft 9, weights 14 rotationally driven at an increased speed by the planetary set-up gear 13, and brake shoes 15 for braking the rotation of the drive shaft 9 through the action of centrifugal force of the weights 14 (See FIGS. 2 and 3).

[0030] In the planetary set-up gear 13, a rotary sleeve 17 is fitted to an end portion of the drive shaft 9 in the tubular casing (a fixed portion) 16 so as to be rotated together with the drive shaft 9, and a first pivot plate 19 by which a plurality of first planetary gears 18 are pivotally supported is fixedly mounted on an end of the rotary sleeve 17 (at the left end as viewed in the diagram), as shown in FIGS. 3 and 4.

[0031] The plurality of first planetary gears 18 are engaged between an internal gear 20 formed around an inside surface of the casing 16 and an external gear 22 formed around a periphery of a tubular portion of a second pivot plate 21 rotatably fitted onto the rotary sleeve 17. The internal gear 20 has the number of teeth larger than the external gear 22. Accordingly, when the first pivot plate 19 is rotated 360 degree, the second pivot plate 21 is rotated at an accelerated speed to the extent corresponding to the number of teeth of the internal gear 20/the number of teeth of the external gear 22.

[0032] Likewise, a plurality of second planetary gears 23 are pivotally supported by the second pivot plate 21. The plurality of second planetary gears 23 are engaged between the internal gear 20 formed around the inside surface of the casing 16 and an external gear 26 formed around a periphery of a tubular portion 25 of a weight supporting plate 24 (mentioned later) rotatably fitted onto the rotary sleeve 17. The internal gear 20 has the number of teeth larger than the external gear 26. Accordingly, when the second pivot plate 21 is rotated 360 degree, the tubular portion 25 of the weight supporting plate 24 is rotated at an accelerated speed corresponding to the number of teeth of the internal gear 20/the number of teeth of the external gear 26.

[0033] As a result of this, the speed ratio between the drive shaft 9 and the tubular portion 25 of the weight supporting plate 24 is the number of teeth of the internal gear 20/the number of teeth of the external gear 22×the number of teeth of the internal gear 20/the number of teeth of the external gear 26. For example, when the number of teeth of the internal gear 20 is set to be 90 and the number of teeth of the external gears 22 and 26 are set to be 45, respectively, the speed ratio=90/45×90/45=4, so that the rotation of the tubular portion 25 of the weight supporting plate 24 is speeded up four times as fast as the rotation of the drive shaft 9.

[0034] The weight supporting plate 24 has a flanged portion formed to project outwardly from a nearly center position of the tubular portion 25 that is fitted onto the rotary sleeve 17 so as to be rotatable relative thereto. The weight supporting plate 24 has the external gear 26 formed around the periphery of the tubular portion 25 at a left side thereof with respect to the flanged portion. The weights 14 are held on the tubular portion 25 of the weight supporting plate 24 at a right side thereof with respect to the flanged portion, so as to be slidable in a centrifugal direction.

[0035] Specifically, the weights 14 are formed by three separate heavy objects formed by splitting a heavy object substantially equally into three pieces extending along a circular arc and are mounted around the periphery of the weight supporting plate 24, as shown in FIG. 4. The three weights 14 have, at substantially center portions thereof, supporting through holes 27 in which three supporting rods 28 standing from the tubular portion 25 of the weight supporting plate 24 at the right side thereof are inserted to support the weights 14.

[0036] Each of the weights 14 has a controlling portion 29 to control the expansion of the brake shoe 15 that is formed to project out horizontally toward the brake shoe 15 along the tubular portion 25, as shown in FIG. 3.

[0037] As shown in FIGS. 3 and 5, the brake shoes 15 are formed by three separate shoe members 30 extending along a circular arc and spaced at a regular interval, and side plates 31, 31 are arranged at both sides of each shoe member 30. Each of the shoe members 30 is pivotally supported by the side plates 31, 31 at one end thereof and is connected to the adjoining side plates 31, 31 through a tension spring 32 at the other end thereof so that it can be elastically biased in a direction for the brake shoe 15 to be contracted in outer diameter by tensile force of the tension spring 32.

[0038] The each shoe member 30 is provided with a lining 33 (a frictional surface) at an outermost portion thereof and is provided with a short cylindrical roller 34 (a frictional contact portion) at an inner portion thereof. The rollers 34 are normally put in press-contact with slant locking surfaces 35 formed in the surface of the rotary sleeve 17 by the tensile force of the tension springs 32, respectively.

[0039] Reference numeral 36 in FIG. 3 denotes securing pins for securing the tubular casing 16. The pins 36 are projected from a base portion of a bearing 37 for rotatably supporting an end of the drive shaft 9 and are inserted in fitting holes 38 bored in a side surface of the tubular casing 16. The fitting holes 38 are formed into elongated form or in the form of slots, as shown in FIG. 6, and cushioning material 39 of silicone gum and the like is packed around the pins 37 in the slots 38. The cushioning material 39 is omissible if a large torque is exerted on it.

[0040] Now, operation of the emergency brake mechanism 1 of the present invention thus formed will be described below.

[0041] When the entrance 5 of the warehouse 4 is covered with the blade portion 3 of the shutter retracted in the winding mechanism 6 provided at the top of the entrance 5 of the warehouse 4, the electric motor 12 of the drive unit 10 is driven first and then is reduced in rotation speed to drive the take-up reel through the drive shaft 9, so as to pay out the blade portion 3.

[0042] As the blade portion 3 of the shutter 1 is gradually paid out, the entrance 5 of the warehouse 4 is gradually covered with the blade portion 3 of the shutter 1, while simultaneously the opposite torque resulting from the weight of the blade portion 3 acting on the drive shaft 9 is gradually increased and thus the rotation speed of the drive shaft 9 is gradually increased.

[0043] Along with the increase in rotation speed of the drive shaft 9, the rotation speed of the rotary sleeve 17 of the brake unit 11 of the emergency brake mechanism 1 arranged at the end of the drive shaft 9 is also increased and is further accelerated by the planetary set-up gear 13, to rotate the weights 14 at a high speed.

[0044] When the rotation speed of the drive shaft exceeds a predetermined lowering speed, the weights 14 centrifuged and acceleratedly rotated is forced to move toward the inside surface of the casing 16 by the centrifugal force, whereby the controlling portions 29 of the weights 14 are operated to expand the brake shoes 15 outward. The control force of the centrifuged weights 14 to expand out the brake shoes 15 forces the brake shoes 15 to move outward against the spring force of the torsion spring 32, so as to bring the linings 33 into frictional contact with the inside surface of the casing 16, so as to reduce the rotation speed of the drive shaft 16 by the friction force.

[0045] Then0 when the rollers 34 of the shoe members 30 run on the slant locking surfaces 35 formed in the surface of the rotary sleeve 17, as shown in FIG. 7, the drive shaft 9 is put into the locked position in which the rotation of the drive shaft 9 is locked to bring the lowering of the blade portion 3 of the shutter 1 to a halt.

[0046] When the rotation of the drive shaft 9 is slowed down and halted by the friction force by the linings 33 and the lock by the lock mechanism, the centrifugal force of the weights 14 is reduced, so that the brake shoes 15 are returned back to the original position by the spring force of the torsion springs 32. These motions are repeated, so that the rotation speed of the drive shaft 9 is controlled within a predetermined rotation speed range.

[0047] While the embodiment illustrated above has the structure wherein the short cylindrical rollers 34 (frictional contacting portions) are provided at the inner portion of the shoe members 30 and are put in press-contact with the slant locking surfaces 35 formed in the surface of the rotary sleeve 17 by the tensile force of the tension springs 32, respectively, within the predetermined rotation speed range, the present invention may be modified, for example, by replacing the rollers 34 with oval brace members 34 and replacing the slant locking surfaces 35 formed in the surface of the rotary sleeve 17 with concaves 35 for supporting the bottom ends of the brace members 34, so that the brace members 34 can be put in the standing position to strongly halt the drive shaft 9, as shown in FIG. 8.

[0048] Also, the brake mechanism 1 of present invention is applicable not only for the emergency brake mechanism for the shutter to cover the entrance of the warehouse as illustrated above, but also for a speed regulation mechanism of an elevator, a battery car for a physically disabled person and an emergency man lift.

[0049] As mentioned above, since the emergency brake mechanism of the present invention is so structured that the rotation input shaft is increased in rotation speed by the planetary set-up gear to centrifuge the weights, so that through the action of the centrifugal force of the weights, the linings of the brake shoes are brought into press-contact with the fixed portion, to reduce the rotation of the rotation input shaft, a large braking power can be produced for a compact emergency brake mechanism.

[0050] This can provide the result that the emergency brake mechanism of the present invention can be mounted to the rotation axis of low rotation speed, such as the rotation axis of the shutter of the factory or warehouse and the rope winding shaft of the emergency lift. For example, when the emergency brake mechanism of the present invention is applied to the shutter and the shutter is pulled down, the rotation axis can be prevented from being rotated at an increased rotation speed resulting from its own weight and the downward inertia force, differently from the prior art. This can provide the advantage that when the bottom end of the shutter gets down to the ground, generation of large impact and noises can be prevented and also possible accidents of one's fingers or toes being caught in or pinched between the shutter and the ground and injured or cut off can be prevented. When the emergency brake mechanism of the present invention is applied to an escape lift with a gondola, the lowering speed of the gondola can be made stable, thus providing the advantage of providing an improved stability for the escape lift with gondola. 

What is claimed is:
 1. An emergency brake mechanism comprising a planetary set-up mechanism provided between a rotation input shaft and a fixed portion; weights; and brake shoes, wherein the brake shoes are so arranged on the rotation input shaft as to be in association with it and the weights are centrifuged by an increased rotation speed produced by the planetary set-up gear, so that through the action of the centrifugal force of the weights, friction surfaces of the brake shoes are brought into press-contact with the fixed portion, to reduce rotation of the rotation input shaft.
 2. The emergency brake mechanism according to claim 1, wherein frictional contact portions are formed in the brake shoes at portions thereof on the drive shaft side, so as to be directly or indirectly contacted with the drive shaft, and the portions of the brake shoes with which the frictional contact portions are brought into contact are formed in the form of slant locking surfaces.
 3. The emergency brake mechanism according to claim 1 or 2, wherein the rotation input shaft is a winding shaft of a shutter and which is so structured as to control a lowering speed of the shutter. 